Charging systems have been proposed in which vehicle passing judging devices are set on plural routes on toll roads or the like, and it is judged what route of the plural routes has been traveled. One example thereof is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 9-212794. In this type of conventional technique, at the vehicle passing judging device, it is judged which path of plural paths has been traveled. Then, a traveled distance is specified in accordance with the path, and a fee is charged in accordance with the specified traveled distance. The object of this type of system is to broadly spread such road charging to users of the road and to make traffic smooth. However, in this structure, infrastructure costs are required. By using GPS positioning and/or dead reckoning navigating, it is confirmed that a vehicle has traveled through a charge area. By subtracting a charge of that amount from the remaining balance of a prepaid card or an IC card or the like, facilities on the road are substantially eliminated, and charging can be carried out.
Dead reckoning navigating uses a gyro (angular velocity sensor+integration circuit) in order to know the advancing direction, and uses a vehicle speed pulse signal in order to compute the traveled distance. The vehicle speed pulse is a signal at which a signal switches H/L for each given distance, and is utilized in vehicle speed detection and the like. Dead reckoning navigating is mainly used interpolatingly in a case in which positioning using GPS satellite cannot be carried out. A drawback of dead reckoning navigating is that, even if the initial position is accurate, the positional accuracy gradually deteriorates in proportion to the traveled distance. Further, with GPS positioning as well, there are cases in which an error of about 100 m arises. In a general navigation system, the position is corrected and map matching is carried out in accordance with link information (angles, lengths, connections, and the like) of roads in a map database which is stored on a mass storage medium such as a CD-ROM or the like. Namely, the road which is closest to the ground position computed by GPS positioning or dead reckoning navigating is detected on a map, and the ground position information is corrected to the position on that road.
In a case in which an attempt is made to realize charging processing by GPS positioning or dead reckoning navigating, in order to recognize the accurate position, each time a most recently traveled locus is held and a new ground position is computed, the traveled locus must be updated, the computed position must be placed on a map, and that position, which matches the traveled locus, on a road on the map must be detected. Namely, the road, which matches the computed position and the traveled locus, and the position on the road must be specified on a map, and that position must be corrected as the ground position (current position). To this end, a detailed map database is required. However, a charging system, which combines a detailed map database for recognizing an accurate position with GPS positioning and dead reckoning navigating, is extremely expensive, which is an impediment to the popularization thereof.